alz0rz

iTrader: (41)

Any particular reasons why my LTFT would suddenly settle at +15%?

I do have my ECU flashed with a work-in-progress AP map (based off myriadshalaks) work. I'm not going to say i'm a pro at it, but I do know what I'm doing when I mess with a cell/variable in Accesstuner RACE. I only touch what I know.

With that said, I am running an AEM intake and the MAF scaling on the AP map is stock. So I know that people would say that I would need to re-scale my MAF due to the AEM intake as that is what is throwing off my trims.. but I don't think so. Before this sudden jump my LTFT settled at +/- 7, and STFT was -1,0,1. It stood this way for a while, and I haven't edited this map since then. I occasionally did monitor my LTFT and STFT and they were as I said above, but today I checked them and the LTFT was at 15%.

I reflashed the Cobb stock style map to see if it's anything I may have done, and my LTFT immediately shot up to 10%.. I imagine it's going to settle right back at where the other map was after a few drive cycles..

So basically, I am asking is, what would offset my LTFT that high? I understand the basic principle of fuel trims and why they exist... so for some reason my ECU is adjusting the fuel delivery by enrichening it by 14-15% due to some unseen factor..? Could it be my fuel pump? MAF? Could engine health (compression, I have reason to suspect this) have any correlation to this?

My ignition is completely up to snuff.

I am catless.

I have checked the obvious vacuum lines to see maybe there was some un-metered air sneaking in.. but everything looks okay..

My last tank of gas was absolutely dismal, 10.5mpg. Of course if the mixture is being enriched by 15% I guess that is to be expected... (do I have the right train of thought on this?)

Please, any ideas would help.

MazdaManiac

iTrader: (3)

Vacuum leak, break in the MAF wiring, loose ground on the support behind the rad, failed evap solenoid, etc.

You didn't say what range it jumped in. Just idle?

alz0rz

iTrader: (41)

Yeah, noticed it at idle. When I'm accelerating the LTFT goes to 0 until I'm back at idle.

I'll recheck the vacuum lines again this weekend. Any other vacuum sources I should check besides the obvious? Will check grounds...

I checked the MAF wiring today when I took out the MAF to clean it.. looked to be fine..

Would engine compression have any effect on the fuel trims?

MazdaManiac

iTrader: (3)

How about after a few days of normal cruising?

Evap loop on top of the manifold, nipples on LIM, solenoid reserve tank source (w/checkvalve) behind UIM, VFAD source, EVAP solenoid (near TB, under UIM), MC booster source, injector "O" rings.

Are your reported MAF values the same as before?

Not really. Not just at idle, anyway (unless you had a completely dead rotor).

alz0rz

iTrader: (41)

Well today was the first time I noticed it.. gonna drive on it a few days and check the LTFT again. At this point I'm back on the Cobb "Stock" Style map... I would uninstall the AP completely but then I wouldn't be able to monitor the trims and you did say the Stock style map for all intents and purposes is the same as the MSP16 flash.

Will check all those on the weekend.

Hadn't checked the MAF values anytime recently. After that tune I had was running smoothly I didn't do much other then occasionally view the Equiv Ratio on redline to see if it was still safe, and checked the LTFT/STFT every so often. That tune was pretty solid.

However, what I did notice on a few occasions was that my N/A renesis would report 250g/s MAF numbers on redline pulls in 2nd and 3rd.. at the time I thought that was a bit abnormal. That's what made me think at the time that the MAF needed to be scaled for the AEM intake and therefore my trims would be off?... but then again the AEM and the Stock intake piping has the same ID?

alz0rz

iTrader: (41)

So yeah, my LTFT keeps settling back at +12% or higher after a few drive cycles.. checked all the vacuum connections I could and everything seemed to be okay.

I did do a compression test on the car as well (with the Mazda rotary compression tester) and I got some depressing numbers.. 4.9,5.0,5.1 on the front rotor and 5.1,5.3,5.6 on the rear rotor.. but that's for another thread.

Brettus

iTrader: (2)

Sounds like your ecu is consistently adding fuel at idle and has always done this . Rescale the maf from zero to about 8g/s by say +10% and see what happens .
Sounds like cruise is ok .

alz0rz

iTrader: (41)

That;s the thing.. it didnt always do this. Before this it was holding steady at +7% LTFT, nothing more. Then it just shot up to 15%. Anyway, so last night on a cruise I watched the LTFT jump up from 0% AT CRUISE to 5% AT CRUISE and creeped up to 7%. When I went back to idle it was at 14% LTFT.. blahhh

Brettus

iTrader: (2)

To me it seems like you need to rescale the maf . Kane did a diy on this a while ago .

Fuel trims do jump around a little even when everything is set correctly but yours does need some tweaking from the sound of it .

arghx7

why don't you just put the stock intake back in? putting aftermarket intakes on modern cars rarely gets you any noticeable performance benefit (something you can actually feel when driving).

but if your compression is really that low then you should pull your motor and have it rebuilt soon. it's cheaper to rebuild a tired motor than a blown one.

alz0rz

iTrader: (41)

/\ Because I'm still under warranty and I don't need to bother rebuilding it when they can replace it for free.

I installed the intake for the sound. And if anything, the lower intake temps in the summer.

MazdaManiac

iTrader: (3)

A sudden change means something changed. Plain and simple.
Rescaling it might mask the change, but I'd want to know what happened first.